1. Field of the Invention
The present invention relates to a microchip, measurement system and method using the same, and a test reagent that is used for a microchip. A microchip is used for biochemical tests of DNA, protein, cell, immunity, blood, and the like as well as environmental analysis and chemical synthesis, for example.
2. Description of the Background Art
In recent years, in the fields of medical care, health, food, drug discovery, and the like, detection or quantitation of biological substances such as DNA (Deoxyribo Nucleic Acid), enzyme, antigen, antibody, protein, virus, and cell as well as chemical substances has become increasingly important, and various biochips and micro chemical chips (such chips will hereinafter be collectively referred to as microchip) with which the above-described substances can be easily and conveniently measured have been proposed.
The microchip can be used to allow a series of experimental and analytical operations usually performed in a laboratory to be conducted within the chip of several centimeters to 10 centimeters per side and approximately several millimeters to several centimeters in thickness. The microchip accordingly provides many advantages that the amounts of samples and reagents to be used are very small, the cost is low, the reaction rate is high, high throughput test or analysis can be conducted, and the test results can be immediately obtained at the site where the sample was taken, for example.
The microchip has a fluid circuit therein. The fluid circuit is mainly constituted of: portions including, for example, a reagent retaining portion for retaining a test reagent to be mixed or reacted with a sample (such as blood) to be tested or analyzed or to treat the sample, a measuring portion for measuring the sample and/or test reagent, a mixing portion for mixing the sample and the test reagent together, and a detecting portion for testing or analyzing the liquid mixture; and a fine fluid channel appropriately connecting these portions. For use, the microchip is mounted typically in a device that can apply a centrifugal force thereto. By applying a centrifugal force in an appropriate direction to the microchip, treatments such as measurement of a sample (or a specific component in the sample) and/or a test reagent, mixing of the sample (or a specific component in the sample) and the test reagent together, and introduction of the obtained liquid mixture into the detecting portion can be performed. It is noted that treatments of various fluids (such as a sample, a specific component in the sample, a test reagent, or a mixture or a reactant of two or more types thereof) performed in the microchip, such as transfer from a portion to any other portion, measurement, and mixing of the fluids will hereinafter sometimes be referred to as “fluid treatment”.
Various microchips including such a fluid circuit have been disclosed (see for example Japanese Patent Laying-Open No. 2006-239538). However, in a measurement method using such a conventional microchip, one detecting portion (optical cell) has been able to perform measurement on only one test item. Thus, in order to perform measurement on a plurality of test items, a plurality of optical cells (cuvettes), optical systems, and the likes have been required.
In addition, in such a case where a fluid treatment is performed by application of a centrifugal force, when a metal colloid reagent is used as a test reagent, since metal has a specific gravity (e.g., Au: 19.3, Pt: 21.45, Ag: 10.49) that is greater than the water's specific gravity of 1, application of a centrifugal force in the fluid treatment may cause metal 5 to separate in a liquid mixture 31 containing a gold colloid reagent, as shown in FIG. 14.